A resin molding product having a fine pattern is useful such as an optical element (such as a micro lens array, an optical waveguide, an optical switch, a Fresnel zone plate, a binary optical element, a blaze optical element, a photonic crystal), an antireflection filter, a biochip, a microreactor chip, a recording medium, a display material, a catalyst support, or the like. In recent years, there has been a demand for further refinement of such patterns, along with a demand for miniaturization of devices. As a method for manufacturing a resin molding product having such a fine structure on the surface, there has been suggested a method for manufacturing an imprint product having a fine pattern formed thereon by transcribing the pattern on a mold having a fine pattern to a resin, that is, a so-called nanoimprint method (for example, Patent Document 1 and Patent Document 2). Furthermore, as a method substituting for a photolithographic method in a process of manufacturing semiconductor, there has been suggested a nanoimprint method of applying a resist on a silicon substrate, pressing thereon a mold on which a fine pattern is formed, and thereby transcribing the fine pattern onto the resist (for example, Patent Document 3 and Patent Document 4).
However, all of the above-described nanoimprint methods have problems that the shape accuracy of the fine pattern in an imprint product is decreased because the mold can not be smoothly released in a process of releasing the mold. Thus, in order to smoothly release the mold, a method of applying a release agent on the mold surface has been attempted. In this case, there is a problem in which the pattern accuracy of the mold is decreased due to unevenness of the thickness of the release agent layer, and there is also a problem in which the releasing agent layer becomes thinning when the mold is continuously used, and it is necessary to reapply the release agent on the mold, which lowers productivity.
In order to solve these problems, a method of using a non-adhesive material having a surface energy of less than about 30 dyn/cm as a mold material (Patent Document 5) has been suggested. Examples of the non-adhesive material include fluoropolymers such as a fluorinated ethylene-propylene copolymer and a tetrafluoroethylene polymer; fluorinated siloxane polymers, and silicones.
However, the method described in Patent Document 5 is to imprint a mold or its negative pattern made of a non-adhesive material onto a photocurable or thermosetting thin film formed on a substrate. That is, the method involves use of a mold pattern or its negative pattern as a lithographic tool. In Patent Document 5, the non-adhesive material is mainly intended to play the role of a releasing agent. Furthermore, a mold using silicone has a low elastic modulus, and it is difficult to imprint a pattern shape accurately as using such a mold.
Furthermore, Patent Document 6 discloses a method of forming a pattern on a transfer layer, which consists of a thermoplastic resin containing a fluorine-containing polymer which has 35% by mass or more of a fluorine content, is pressed with a mold having an inverse pattern of a desired pattern, and thereby forming the desired pattern on the transfer layer; and a step of releasing the mold from the transfer layer. It is described in the document that this method is excellent in the releasability of the transfer layer from a mold and thus can form a fine pattern. Examples of the fluorine-containing polymer include polytetrafluoroethylene, a 1,1,1-trifluoro-2-trifluoromethylpenten-2-ol copolymer, a perfluoro cyclic ether polymer (trade name: Cytop (registered trademark)), and a copolymer of chlorotrifluoroethylene and vinyl ether (trade name: Lumiflon (registered trademark)).
However, when the fluorine content of these polymers is 60% by mass or less, their dimensional accuracy in terms of the depth, width and interval of convex structures is low and dimensional difference is large, because the elastic modulus is rapidly decreased at a temperature above the glass transition temperature, and after the polymer is subjected to press molding, when cooling rapidly, the shrinkage ratio is increased due to the decreased elastic modulus. In addition, even if fluorine content is 60% by mass or more, the fluorine resins such as polytetrafluoroethylene which exhibit a high melting point temperature (Tm), although it is necessary to set the molding temperature markedly higher, provide significant differences in the dimensions between the convex structure mold and the imprint product because of increase in the differences between the elastic modulus and shrinkage ratio during the process of heating and cooling. Furthermore, the fluorine resins must be decomposed when heated at temperature of 300° C. or higher to generate hydrogen fluoride gas, which associate with a high possibility of decomposition of the fluorine resins when heated at the temperature of 260° C. Thus, problems such as corrosion of the mold and peripheral devices, or environmental contamination, are caused.
The imprint methods which comprise molding by heat press as suggested as described above, are required to uniformly put high pressure on a large area in order to obtain an imprint product with a large area, and thus a large-sized heat press molding machine is necessitated. Thus, there is a large problem in manufacturing an imprint product with a large area because of limitations on the area of the imprint product that can be industrially processed.